Distribution of electric currents



(No Model.) 2 Sheets-Sheet 1.

E. THOMSON. DISTRIBUTION OF ELECTRIC GURRENTS.

WITNESSES: INVENTOR ATTORNEY.

(No Model. 2 Sheets-Sheet 2.

E. THOMSON.

DISTRIBUTION OF ELBOTRIG OURRENTS. No. 425.470. Apr. 15,1890.

INVENTOR I WITNESSES:

ATTORNEY.

UNITED STATES PATENT OFFICE.

ELIHU THOMSON, OF LYNN, MASSACHUSETTS, ASSIGNOR TO THE THOMSON- I'IOUSTON ELECTRIC COMPANY, OF CONNECTICUT.

DISTRIBUTION OF ELECTRIC CURRENTS.

SPECIFICATION forming part of Letters Patent No. 425,470, dated April. 15, 1890.

I Application filed January 29, 1890. Serial No. 338,526- INo model.)

To all whom it may concern:

Be it known that I, ELIHU THOMSON, a citizen of the United States, and a resident of Lynn, in the count-y of Essex and State of Massachusetts, have invented certain new and useful Distribution of Electric Currents, of which the following is a specification.

My invention relates to systems of distribution of electric currents wherein the prime to generating source furnishes energy which is carried over mains or conductors to a considerable distance therefrom. In systems of this character there is, as is well known, a drop of potential at distant points, owing to losses due to the resistances or other causes, and in order to obtain a potential overthe whole system as nearly uniform as possible it becomes necessary to use main conductors of very great size or to employ some means for maintaining or supplementing the potential at the more distant points, if it be desired to have a uniformity of potential throughout the system. It is also common in such systems to provide some means to regulate the potential over the system in accordance with variations in the load or demands made for energy upon the circuits.

One of the objects of my invention is to compensate for or prevent drop of potential 0 which takes place at points in the system remote from the generating source without resorting to the use of heavy or expensive main or feeding conductors.

A further object of my invention is to keep 3 5 the potential at distant points up to the required amount, despite tendency to fall through increase of load, and, in fact, to regulate the potential over the system in such way as to maintain or produce a potential of any desired degree under various conditions.

A. further object of my invention is to provide a system. of distribution having great flexibility and adaptability to wide variations in working conditions.

5 My invention consists, essentially, in sustaining, regulating, or supplementing the potential at distant points of the system by generating currents of comparatively high potential by any desired means, conveying the same over independent conductors or mains to or near the points of the main system where the potential is to be regulated, supplemented,

or maintained, transforming such high potential to reduced potential suitable for feeding to such mains, and applying such reduced potential or energy to the main system at the points where its potential is to be regulated, sustained, or supplemented.

My invention consists, further, in the combination of circuits and apparatus wherebyl am enabled to accomplish the objects of my invention and wherebyasimple and effective regulation for variations in load is obtained, and whereby, further, a maintenance of a uniform potential over a whole system may be automatically produced.

My invention is applicable either to extensive net-works of mains or conductors running at moderate potential for incandescent lighting or for other purposes, as well as to motor-lines which extend to a great distance from a generating-station for feeding stationary motors or for operating the motors upon electric railways.

My invention comprises essentially in the same system of distribution the combination of apparatus feeding currents to a set of mains,a second set of mains or conductors fed with currents of high potential, generated, preferably, at the main station, intermediate transformers between the two sets of mains at one or more points, such transformers being properly constructed to transform or convert the high-potential current into a lowerpotential current, and connections from the low-potential side of the converterto points of the system where the potential is to be maintained, regulated, or supplemented. In other words, it comprises in the same system a set of mains extending from a generating-station 0 to a considerable distance therefrom, and a set of mains of higher potential carrying current which operates transforming apparatus that in turn supplies the proper potential to the more distant portions of the lower-potential mains or conductors. Owing to the use of the higher potential, the distance is overcome without great losses, and the necessity of large-sized conductors on the lower potential mains for the purpose of preventing drop of potential is avoided.

The transformers or devices for converting I the high potential into low potential may be of any desired character. They may be, for instance, the well-known device of a motorgenerator in which the motor is an electric motor driven by the high potential, and the generator mechanically operated by such motor is provided with armature coils or 0011' ductors adapted to deliver the current of lower potential, or they maybe the well-kn own form of converter or transformer consisting of an induction-coil in which the conversion takes place by direct inductive action between two coils wound in inductive relation to one another on the same core.

In the accompanying drawings, Figure l is a diagram illustrating my invention. Fig. 2 illustrates the application of the invention to alternating-current systems of distribution.

In Fig. 1 the devices are adapted to generate continuous currents.

M M are mains or conductors, which are supplied with energy from a dynamo-machine G, of any suitable character. The generator G may be of any proper character adapted to supply current of regulated potential, or may be of any other proper character for supplying current to a system of mains or conductors. The mains M M are the main supply-conductors from which the energyusers-such as incandescent lamps L L, motors S, or railway-motors Tderive current.

At or near the points of the main system supplied bygenerator G, where the potential is to be supplemented, regulated, or re-enforced, I place transformersB B, (here shown as combination motors and generators,) which are properly wound or organized in such manner that by the application of the high-potential current they will revolve and give out low-potential currents proper for feeding the mains M M, to which they are connected. The motor-generat0rs here shown have their two sets of coilsto wit, the motor and generator coils-wound on the same armature. The high-potential current which works such motor-generators, and which is transformed, is supplied over a main or mains H H, which derive their high-potential current from a generating source G, that may be a dynamogenerator. This dynamo-generatormight be a com pound-Won nd dynamo, a shunt-dynamo, a separately-excited dynamo, or any other form of machine; or, in place of a dynamo, any other source of current of higher potential than that supplied to the mains M M might be used. It is well to use a potential as high as practicable under the conditions of use, in order that the lines H II maybe of as small gage as possible. The transformers are supplied with such high-potential energy in any desired manner, but, preferably, are connected in multiple to the high-potential lines, and the high-potential generator is of such character as to supply a regulated potential to the lines II II, or, in other words, one of constant or approximately constant amount.

The generator G, if a dynamo-machine,

might be driven by any suitable power and in anysuitable manner; but I prefer to have the machines G G interdepemlent, so that they shall be operated always at the same relative speed. By this means I secure regularity and uniformity in output of the machines relatively to one another and a uniformity of operation under various conditions of the system.

By the use of the supplemental mains of high potential I am enabled to use mains M M of moderate dimensions and at the same time to secure a uniformity of potential over the whole system.

Suitable fuses may be interposed in both the high and low potential circuits, as indicated at points F F, and switches for cutting off or disconnecting any portion of the circuit may be established at any desired point or points, as at Z.

By the use of the transformers such as i11- dicated having the double-wound arn'iaturcs and by running them at high speed in stronglymagnetized fields, the high potential of the high-potentiz'tl circuit will be transformed to give current to the other circuit with a lower potential and with extremely small loss in the transformation. The machines or converters will also respond to the call upon them for more energy as it is required,tl1us giving the effect of an automatic supply of current in accordance with the demand of the main circuits M M. So long as the potential of the mains M M is maintained at its regulated 01' normal amount and very little call exists for current from the transformers B B, the latter will do little or no work and the generator G can be made to deliver all the current needed. If, however, at a distant point 011 the mains M M, near the point of attachment to one of the transformer-machines B B, a sudden heavy call for current takes place, then such machine B B becomes at once a powerful and efficient generatorof low-potential current, which is fed to the mains M M. to sustain their potential at the same time that a considerable high-potential current from the mains II II flows to the converter, the amount depending upon the potential of the mains relatively to one another. At the same time this occurs the generator G is called upon for additional output, while the generator G may do little work, if any. If the call, however, for current is upon the mains M M near the generating-station, or the place where the wires from G are attached, then but little call will be made on the distant transforming-machines and the work will be fed directly from the station at low potential. My system, therefore, permits the feeding at uniform potentials to lines extending over a very large area or at considerable distances from the gencrating-station, as is the case with railways extending several miles therefrom.

lVhen the load is light upon the mains M M, as by the cutting off of the lights, &c.,

then it will seldom be necessary to maintain the action of the transforming-machines B B, &c., and they can readily be cut out of circuit by the switches provided, as at Z Z, &c. In fact, if no call exists 011 the high-potential line H II for current, it can be cut off altogether, or the machine G be shut down, while G remains to supply the current; hence the system is a very flexible one and can be adapted to a variety of circumstances or needs.

In Fig. 2 the system is shown modified for application to an alternating system for feeding lights. The generator G would, as before, feed mains M M at low potential, and branches from the latter mains existrunning as desired to lights, as described, over a district, as at L. The high-potential mains H II are fed from another generator G, or from a portion of the first generator if properly organized, and the potential is only limited by the insulation of the line. At suitable points transfer devices-such as induction coils, converters, or transformers-are established for lowering the potential of the current feed ing the line H H to that needed to supply the line M M, as before, suitable cut-off devices and other similar appliances being in all cases understood as provided. The transformers in this case are simply inductioncoils made in the ordinary way for such purposes, and the relation of the windings is such as to suit the relations between the potentials of-II H, or high-potential mains, and M M as low-potential mains. The transformers B B feed the mains at the distant points, while the direct feeding of M M by the generator G is to those points near the station, especially when the load on the whole system is considerable. There is nothing to prevent, in the extension of such a system as I have described, the addition of athird generating-machine or a third and still higher potential for distribution to the still more dis tant points, though this is unnecessarily complex, for. the reason that the high-potential line H II may feed potential sufficient to reach the more distant points and still be ap plied to feed the points much nearer to the generatin g-station.

The operation of the generators G G to gether in Fig. 1 may be accomplished by mounting their armatures on the same shaft with an intermediate clutch, as shown, whereby, in case the generator G be not required, the generator G may be alone operated. Ido not limit myself, however, to any particular way of driving such generators together.

While I have shown two forms of convert ers or transformers adapted for transforming the high potential into low potential, I do not limit myself to these special devices, as any means adapted to convert the high-potential currents, whether continuous or alternating, on the one circuit into the required low po tential or supply to the other portion of circuits or part of the system may be used witlr 'out departing from the spirit of my invention,

which consists not only in the particular combinations of circuits and apparatus herein described, but also, broadly,in the method of maintaining the desired potential at points in the system of distribution remote from the supply-station by supplying such points with electrical energy in two ways-one by a lowpotential generator and the other by the transformation of highpotential energy into a proper low-potential energy through devices fed from high-potential mains or circuits. It will of course be understood that in the case of main conductors M H of great length it will be necessary in case a uniform potential is desired over the whole system to adapt each one of the transformers B B to its particular location, and in the case of the t 'ansformers more remote from the main station to wind or construct them so that the potentials delivered to the mains M M will be greater the farther the transformer is removed from the main station. In the case of the use of alternating currents it will be understood that the synehronism of the phases of the directly-supplied waves and the waves of the current supplied by induction will be required. This can be done by the relation of the rotating parts of the generating-machines.

IVhat I claim as my invention is- 1. The herein-described method of maintaining or regulating the potential at any point of a system of electrical distribution, consisting in supplying energy thereto from two sources, one connected therewith over one set of mains or conductors and the other indirectly connected therewith through another set of mains or conductors of high potential, from which the energy is transformed to low potential for application to such points.

2. In a system of electrical distribution, the hereiirdescribed method of supplementing the diminished potential at points distant from the main source, consisting in generating an independent current of higher potential, conveying the same to or near the said distant point, and there converting it into electrical energy of lower potential adapted to be carried directly to the conductor whose potential is to be re-enforced.

3. The herein-described method of maintaining or producing the desired potential at any point distant from a main generator, consisting in generating electrical energy of higher potential than that of the main genorator, carrying the same over suit-able eonductors independent of those connected directly to such main generator, and converting such higher potential into a suitable lower potential at or near the point where the po tential is to be maintained or re-enforced, and then feeding such lowerpotential to the main wire or conductor of the system.

l. The lrerein-described method of obtaining a uniform potential at points of a system of distribution located at different distances from the main generator supplying the same, consisting in generating a higher potential by any suitable means, conveying the same over suitable separate conductors to or near the distant points of the system, there converting such higher potential into a lower potential of a suitable amount, and supplying such low potential to the points of the main system.

5. A combined system of generation and distribution of electric currents, comprising at a central station two generating apparatuses of high and low potential, respectively, two sets of mains of high and low potential,

respectively, connections from the low-potential generating apparatus directly to the lowpotential main, connections from the highpotential generating apparatus to the highpotential mains,and devices at a distance, such as transformers, using current from the high potential mains and transforming it suitably for the comparatively low-potential mains.

6. In a combined system of generation and distribution, the combination, substantially as described, of mains M M, fed from a suitable generator, lines H H, supplied with energy of approximately constant potential, transformers connected in multiple to such lines H H and adapted to convert the potential of such mains into lower potential on a separate circuit, and connections from the latter to the mains M M, for feeding such lowered potential thereto, as and for the purpose described.

7 The combination, substantially as described, of mains M M, fed from a generator G, of any suitable description, electric lines H H, leading from the main station and supplied with currents of high potential, and motor-generators adapted to convert such high-potential current into continuous current of lower-potential, such motor-generators being connected to the mains H H at points distant from the main station and being connected to supply continuous current to the mains M M, as and for the purpose described.

'8. The combination, substantially as described, of electricsupply-conductors leading from the same generating-station to the territory to which electric energy is to be furnished and supplied with energy of different potential, transformers located at point-s of the system distant from the main station and adapted to convert high potential into low, and connections from such transformers to the high and low potential mains or circuits, respectively, as and for the purpose described.

9. In a combined system of electrical generation and distribution, the combination, substantially as described, of two sets of mains M M and H H, the generator G, supplying the mains M M, means for supplying the mains H H with a higher potential, and motor-generators connected to the mains H II in multiple and having double-wound armatures, as described, the generator portion of which connects to the mains M M and is adapted to supply thereto electric energy of lower potential than that on the mains H H.

10. The combination, substantially as described, of two dynamo-generators operated constantly at the same relative speed and generating current of diiferent potential, respectively, elcctricconductors supplied with energy from the lower potential generator, conductors carrying current of the higher potential, and transformers between the two sets of conductors for converting the higher potential current into a lower potential, as and for the purpose described.

11. The combination, with mains supplying translating devices in multiple, of supplemental mains carrying current of higher potential, transformers connected in multiple between the latter, and connections from the low-potential side of said converters to the lower-potential mains.

12. The combination, substantially as described, of mains supplying translating devices in multiple arc, mains of higher potential to which transformers are connected in multiple, connections in multiple from the first-named main to the low-potential side of the converter, and dynamo-machines operated constantly at the same relative speed and supplying ourrents of relatively high and low potential to said mains, respectively.

Signed at Lynn, in the county of Essex and State of Massachusetts, this 24th day of January, A. D1890.

ELIHU THOMSON.

'Witnesses:

JOHN W. GIBBONEY, ALBERT L. ROHRER. 

